Limestone Canyon is a nature preserve part of Irvine Ranch Natural Landmarks. In 2006, it was designated a National Natural Landmark by the Secretary of the Interior for its outstanding biological and geological features. Coastal sage scrub and chaparral plant communities cover colorful hills and canyons along with rare and endangered animal species. A geological feature known as 'The Sinks' is the most impressive part of the canyon. *Access is limited to programs with the Irvine Ranch Conservancy
